金属热还原法制备V-Ti基合金的动力学研究

Kinetic study on preparation of V-Ti based alloys by metallothermic reduction method

采用DSC测试技术对金属热还原不同反应体系的放热过程进行研究,并采用Freeman-Carroll法,对相关反应的动力学参数进行计算。研究结果表明:Al与V_2O_5的反应主要为液-液反应,在1 000℃以下就可进行;Al与TiO_2可以以液-固形式反应,但在1 100℃以上时,反应才显著发生;以Al-Ca合金替代Al粉作为还原剂,可以促进热还原反应提前发生,但钙热反应先于铝热反应出现;Al与TiO_2反应的活化能明显高于Al与V_2O_5反应的活化能,反应速率受温度的影响更大;原料中添加一定量Ca O,可以促进Al与TiO_2反应的发生,降低此反应的活化能,但会增加Al与V_2O_5反应的活化能。

The DSC curves were tested to study the exothermic processes of different reaction systems, and the kinetic parameters of the relevant reactions were calculated using Freeman-Carroll method. The results show that Al（liquid） reacts with V2O5（liquid） below 1 000 ℃. However Al（liquid）-TiO2（solid） reaction occurs obviously only when the temperature is higher than 1 100 ℃. If Al-Ca alloy is used as the reducing agent, the thermal reactions appear in advance, and the calcium thermal reductions occur earlier than the thermite reactions. The apparent activation energy of the Al-TiO2 reactions are notably larger than that of Al-V2O5 reactions, and the reaction rates of Al-TiO2 reactions are more sensitive to the temperature. Adding some CaO to Al-TiO2-V2O5 reaction system can reduce the apparent activation energy of the Al-TiO2 reaction, but it can also increase the apparent activation energy of the Al-V2O5 reaction.